1. Field of the Invention
The present invention relates to a pump and, more particularly, to such a pump that can be selectively installed in one of a number of positions to fit different installation requirements.
2. Description of Related Art
In a prosperous, fast developing modem society, people become more critical to the quality of living. The old concept of merely “workable” no longer suffices. Instead, people demand better quality of products. The only way to satisfy such a demand is to keep making improvements on existing products or to even create new products.
U.S. Pat. No. 6,502,394 discloses a new design of pump. As illustrated in the specification of this patent (see FIG. 1 of the cited reference), the prior art pump 10 comprises a housing 30, an end cap 34 attached to the housing 30, and a charge pump 8 connected to the end cap 34. The end cap 34 has two ports 40 for connection to a hydraulic motor 38 by an oil piping system and has an oil port for connection to an oil reservoir through an oil pipe. When the pump 10 is installed in a powered vehicle 48 (see FIG. 2 of the cited reference), the control arm 26 has one side extended to the outside of the housing 30 to operate the vehicle. However, because the end cap 34 of the pump 10 has only one installation direction relative to the housing 30, the ports 40 of the end cap 34 allow the connection of pipes in one single direction only. This limitation results in a complicated arrangement of pipes between the pumps 10 on the right and the left side of the said vehicle, and the oil reservoir. As shown in FIG. 4 of the cited reference, in order to arrange the pipes in a good order, the control arm 26 of one pump 10 must be attached with a U shaped link 46. The use of the U shaped link 46 greatly complicates the installation procedure and increases the installation cost.
To eliminate the aforesaid limitation, a pump 50 as shown in FIG. 5 of the cited reference was developed. This pump 50 comprises a pump housing 54, an end cap 56 attached to the pump housing 54, and a charge pump 122 connected to the end cap 56. The end cap 56 has two ports 68; 70 connected to a hydraulic motor 38 through oil pipes 44 and an oil port connected to the oil reservoir. As shown in FIGS. 4 and 4B of the cited reference, the end cap 56 has two installation positions that eliminate the aforesaid limitation.
However, this design of pump still does not function satisfactorily. Because the ports 68;70 are provided at the end cap 56, pipes can be connected to the pump 50 in two positions only. Further, if an obstacle is in the way and the pipes 44 cannot be connected to the ports 68;70, the end cap 56 must be detached from the pump housing 54 and then reinstalled in the pump housing 54 after changing the direction to have the pipes 44 connected to the ports 68;70. This position changing procedure is complicated. Further, because the end cap 56 has only two installation positions, the pump 50 still does not fit different installation conditions.
Therefore, it is desirable to provide a pump that eliminates the aforesaid drawbacks.